This application claims Paris Convention priority of DE 199 57 332. 8 filed Nov. 29, 1999 the complete disclosure of which is hereby incorporated by reference.
The invention concerns a transverse connector for osteosynthesis for connection of a fixation rod interconnecting several vertebrae.
Curvatures of the spine are conventionally treated by interconnecting several vertebrae via a fixation rod and are thus correctly positioned. Towards this end, pedicle screws are screwed into the vertebrae or bone plates are disposed on the vertebrae into which the fixation rod or, optionally, several fixation rods are introduced. With extreme curvatures of the spine, the curvature of the fixation rod may not be sufficient for binding the vertebrae, the bone screws screwed into the vertebra, or the disposed vertebrae plates to the fixation rod. For such curvatures of the spine, several fixation rods, which are connected to one another, must normally be used so that several bone screws have to be screwed into the individual vertebrae. This can cause problems since the strength of the vertebrae suffers.
It is therefore the underlying purpose of the present invention to provide a transverse connector which can also correct extremely curved spines.
This object is achieved in accordance with the invention with a transverse connector for osteosynthesis, wherein the transverse connector comprises a rod-shaped section to fix same and a clamping section for connecting the fixation rod.
The transverse connector in accordance with the invention facilitates use of fixation rods which are less curved even in the event of extremely curved spines, wherein the fixation rods are connected to the bone screws or bone plates and thus to the vertebrae via the transverse connector in accordance with the invention should direct connection of the fixation rod to the bone screws or bone plates not be possible. The transverse connector in accordance with the invention can thus safely transfer, without play, the correction forces from the fixation rod to the corresponding vertebrae. The transverse connector is connected either to the bone screw or to the bone plate via the rod-shaped section, wherein the fixation rod is mounted to the transverse connector via the clamping section.
A further development provides that the clamping section has an opening for receiving the fixation rod, said opening having a slot which is open at an edge. The fixation rod is guided through the opening and retained by reducing the cross-section of the opening after insertion of the fixation rod. This is usually effected by screwing in a screw to reduce the size of the slot and thereby clamp the fixation rod in the opening. It is also possible to screw a fixation screw into the clamping section which directly engages and holds the fixation rod. Clamping screws of this type are usually designed as stud screws.
In a preferred manner, the clamping section is formed in two pieces, with a clamping lid. The clamping lid thereby forms part of the opening for the fixation rod. This embodiment of the clamping section has the essential advantage that the fixation rod can be inserted into the opening in a relatively simple fashion and that the clamping lid is disposed only after insertion or introduction of the fixation rod to thereby close the opening.
The clamping lid is disposed on the rod-shaped section in a preferably pivotable fashion. The fixation rod can be removed relatively easily by pivoting open the opening and the opening is closed after insertion of the fixation rod by pivoting closed the clamping lid, as mentioned above.
In a preferred embodiment, the clamping lid has a shackle surrounding the rod-shaped section of the transverse connector thereby securely retaining the clamping lid. Moreover, the shackle transfers the clamping and retaining forces of the clamping lid to the rod-shaped section.
An embodiment provides that the shackle bends away from the plane of the clamping lid through an angle of about 900xc2x0 and surrounds the rod-shaped section orthogonally to its longitudinal axis. This embodiment of the shackle permits pivoting or raising of the clamping lid while facilitating optimum force introduction and fixation of the clamping lid on the rod-shaped section.
To produce a defined position of the clamping lid, the shackle comprises a shoulder forming a bearing which is supported on a counter bearing of the other part of the clamping section. The two parts of the opening into which the fixation rod is inserted are also aligned with respect to one another via these two bearing parts.
In a preferred fashion, the bearing with associated counter bearing and the clamping screw are disposed on opposite sides of the opening for the fixation rod. The shackle surrounding the rod-shaped section is also disposed on the side of the bearing with associated counter bearing. This embodiment guarantees that even large forces can be easily introduced from the fixation rod into the transverse connector without changing the position of the fixation rod in the clamping section.
Further fixation against displacement and/or turning of the transverse connector in the bone screw or the bone plate is provided when the rod-shaped section has a surface structure having, in particular, grooves extending in the longitudinal direction. A surface structure, in particular comprising grooves extending in the longitudinal direction of the opening, can furthermore be provided on at least sections of the inner surface of the opening for the fixation rod. This surface structure prevents change of the position of the structural component in the associated clamping element. Other surface structures, such as fluting, a threaded structure etc. are also feasible.
In order to be able to easily use both fixation rods as well as the inventive transverse connector on the same bone screws and/or bone plates, the diameter of the rod-shaped section corresponds to the diameter of the opening for the fixation rod, wherein the transverse connector does not require any special bone screws and/or bone plates.
Surgery is facilitated when the clamping section has a securely fastened screw. This precludes parts of the transverse connector from becoming lost after insertion of the transverse connector and before the final clamping of the fixation rod. The screw for mounting the clamping lid is always securely retained on the clamping lid.
Further advantages, features and details of the invention can be extracted from the dependent claims and the following description describing, in detail, a particularly advantageous embodiment with reference to the drawing. The features shown in the drawing and mentioned in the claims and the description may be essential to the invention either individually or collectively in any arbitrary combination.